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INFRARED REFERENCE SPECTRA

APPENDIX 13 INFRARED REFERENCE SPECTRA

Introduction

          This section of infrared absorption spectra consists of a collection of reference spectra for use in conjunction with the analytical specifications that are contained in the monographs.

          The infrared spectroscopy is useful as a means of verifying identity of the substances in the monographs, which can be performed by comparing with the TP infrared spectra or spectra prepared from reference substances similarly treated. The advantage of publishing these spectra is principally that substantial economies of both time and expense will be effected by allowing a reduction in the number of Reference Substances to be collected by the drug manufacturers and the laboratories concerned.

Reference Spectra

          The differences of a spectrum obtained from one laboratory to another may be associated with the use of different types of instruments. A major contributory cause to such differences would be the nature of monochromator whether prism or grating. Spectra of TP substances were recorded on a nondispersive multiplex instrument employing the Fourier transform. As an aid to comparison, a Reference Spectrum of polystyrene film is presented with the recommendation that a similar spectrum be prepared on the instrument being used to carry out the test.

Preparation of Spectra

          All reference spectra were prepared by Department of Medical Sciences, Bureau of Drug and Narcotic and recorded on a Jasco model 4100 fourier transform infrared spectrophotometer.

          The substances used for the preparation of reference spectra were USP Reference Standards, BP Chemical Reference Substances, Ph. Eur. Chemical Reference Substances, WHO International Chemical Reference Substances, WHO International Biological Standards and DMSc Reference Standards. In cases the mentioned substances were not available, the high purity substances were obtained from pharmaceutical manufacturers.

          The method for preparation of sample being examined: an approximate 5 per cent of the substance to be examined was triturated and mixed with finely powdered and dried potassium bromide. Place the mixture in a sample cup and examine the reflectance spectrum. The prepared spectra were carefully compared with the approved appropriate reference spectra, using the maxima of a polystyrene spectrum to account for possible differences in wavelength calibration.

          The spectra were labelled with the following information:

          Generic Name

          Phase of the Sample Preparation.

          The spectra were determined in the region from 400 cm–1 to 4000 cm–1 and were represented on a transmittance (%) vs linear wavenumber (cm–1) format. The spectra were labelled in accordance with the final form of the substance and not necessarily with the name of the monograph in question.

APPENDICES • INFRARED REFERENCE SPECTRA
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หมายเหตุ / Note : TP II 2011 PAGE 664-685